【作者】 王萍；

【导师】 江树人； 周志强；

【作者基本信息】 中国农业大学 ， 农药学， 2005， 博士

【摘要】 本论文以手性除草剂乙氧呋草黄为研究对象,以高效液相色谱手性固定相拆分方法为基础,获得了光学纯对映体;利用生测方法对制备的对映体生物活性进行了比较;在此基础上,选择了不同质地的土壤、两种草坪草和动物体为目标,对乙氧呋草黄左右旋对映体的选择性环境行为进行了系统的研究,这是关于该手性化合物对映体生物活性和选择性环境行为的首次报道。 合成了CDMPC手性固定相并制得手性柱,对手性农药乙氧呋草黄和稻丰散对映体具有很好的识别和拆分能力。在优化的半制备色谱条件下,完成了乙氧呋草黄对映体的拆分、收集和制备,两个组分的化学结构经GC-MS确证,光学性质和流出顺序用圆二色检测器和旋光仪进行测定,获得了光学纯度超过97%的左旋和右旋对映体。 选择敏感性适中的高梁、黄瓜和小麦,利用生测技术对乙氧呋草黄外消旋体及左右旋对映体的生物活性进行了研究。结果表明,单一左右旋对映体和等量的外消旋处理的高梁和黄瓜鲜重抑制作用差异显著,右旋体活性明显高于左旋体,也明显高于等量的外消旋体。但是对小麦生长的抑制活性两个对映体表现一致。 草地早熟禾和高羊茅两种草坪草经茎叶喷雾外消旋乙氧呋草黄后,定期采集、处理,分析其体内该手性化合物对映体的选择性降解情况。结果显示,乙氧呋草黄对映体在两种草坪草体内降解趋势基本一致,但降解速度差异显著,存在明显的立体选择性降解现象,左旋体被优先降解,导致体内右旋体过量,最高ER值达到3.0左右。 以大白兔为试验动物,采用静脉注射外消旋体的给药方式,考察了给药后不同时间点的血药浓度以及脑组织、肝脏和胆汁中左右旋体的残留量。结果表明,在供试大白兔体内选择性现象明显,左旋乙氧呋草黄被优先降解或排泄,给药后血浆中ER值迅速增加;药代动力学分析结果显示,药时曲线符合二室开放模型;左右旋对映体的药代行为差异显著,其中右旋体的总体清除率远远低于左旋体,平均持留时间明显比左旋体长,导致其生物利用率AUC远远大于左旋体。乙氧呋草黄对映体在脑组织中存在与血浆中不同的选择性机制,左旋体的浓度高于右旋体;而在肝脏和胆汁中的选择性与血浆中相同,右旋体的浓度高于左旋体。 通过向不同类型的土壤中添加外消旋及单一光学纯对映体进行培养,研究了乙氧呋草黄在土壤中的降解动态和选择性降解情况。结果表明乙氧呋草黄在土壤中的消解符合一级动力学规律,其降解速度受土壤有机质含量和质地等特性影响较大。黑暗培养和光照培养条件对乙氧呋草黄对映体的降解趋势和选择性情况无明显差异。左右旋对映体在3~#土壤中的降解速率有明显差异,二者半衰期相差0.95周;添加外消旋体培养6周后ER值达到1.65,表明左旋体被优先降解;同时在该土壤中存在左旋体向右旋体的转化现象;在其他几个土壤中均未有明显的选择性降解或对映体转化现象。更多还原

【Abstract】 The enantiomeric activity and enantioselective behavior of ethofumesate in organisms and environment were studied based on the HPLC-Chiral Stationary Phase (CSP) technology to provide details of the performance and the fate of its enantiomers. It’s the first report focused on the enantiomeric activity and stereoselective degradation of ethofumesate.The CDMPC CSP was synthesized and the chiral column was prepared which showed favorable enantiomeric recognition and separation potency. Resolution and preparation of ethofumesate enantiomers were achieved under the optimal semi-preparation conditions. The chemical structure of two elutes were identified by GC-MS, the optical property and the eluting order were determined by using the Circular Dichroism detector and polarimeter. The optical purity of each enantiomer was more than 97%.The bioactivity of the enantiomers was studied by bioassay with plant materials showing moderate sensitivity. Results indicated that the (+)-enantiomer showed significantly higher activity on cucumber and sorghum fresh weight inhibition than that of the (-)-enantiomer, and also higher than that of the racemate at the same rate. The two enantiomers, however, showed equal inhibition activity on wheat growth.The investigation was taken on involving stereoselective degradation of ethofumesate enantiomers in Kentucky bluegrass and tall fescue after foliar treatment with racemate. The results revealed the same preferential degradation of the (-)-enantiomer in both grass species. This selective style of degradation resulted in residues enriched with (+)-enantiomer in both species. The largest Enantiomeric Ratio (ER) of (+)/(-) was achieved above 3.0 at 5 days after treatment.The enantioselective degradation and pharmacokinetics of ethofumesate enantiomers in rabbits were investigated by a single intravenous (iv) administration at doses of 30 mg kg~-1 of racemate. Plasma concentration-time curves after iv administration were best described by an open two-compartment model. The concentration of the (-)-enantiomer decreased more rapidly than that of the (+)-enantiomer. Significant differences on pharmacokinetic parameters between two enantiomers indicated that the stereoselective behavior occurred in rabbits after iv administration with racemic ethofumesate. Similarly selective style was found in liver and bile, while reversed distribution tendency was observed in rabbit brain tissue with ER value lower than 1.The dissipation dynamic and the enantioselective degradation of ethofumesate in soils were studied by incubation with either racemate or optical pure enantiomers in different agricultural soils. The dissipation dynamic of ethofumesate in soils fitted to the first kinetic’s law. The dissipation rate was greatly influenced by organic matter and texture style of each soil, while the light showed no influence on it. Preferential degradation of the (-)-enantiomer was observed in 3* soil, which led to the ER of 1.65 after 6 weeks of incubation with racemic ethofumesate. The stereoselective degradation causedsignificant difference on half-life between two enantiomers in this soil. The appearance of (+)-enantiomer after incubation with single (-)-enantiomer revealed the enantiomeric inversion of (-)-isomer to its antipode. While no obvious stereoselective degradation or enantiomeric inversion were observed in other test soils.更多还原